It is known in the art relating to internal combustion engines to utilize pressure sensing devices to indicate the occurrence, magnitude and/or timing of combustion in one or more engine cylinders, or combustion chambers. A sensor may be selected from known devices, such as piezoelectric force rings, and applied together with a suitable indicating or control system as shown, for example, in U.S. Pat. No. 4,153,019 Laubenstein et al, assigned to the assignee of the present invention.
In practice, prior art cylinder pressure sensors have been mounted in various ways to obtain the desired pressure signal for subsequent use in an associated indicating or control system. A known application, referred to in U.S. Pat. No. 4,153,019, is to secure the force ring indicator to the engine by a cylinder head bolt which serves as the combustion pressure signal source. However, such applications are subject to other forces acting on the cylinder heads in addition to combustion pressure such as, for example, thermal expansion and external shock or inertia loads. These extraneous forces may vary, or otherwise adversely affect, the cylinder pressure indications sensed by the pressure sensor and, thus, may interfere with the proper operation of the system to which the cylinder pressure sensor is connected. It is therefore desirable to provide an engine combustion pressure sensor mounting arrangement which avoids or minimizes the application of extraneous forces to the cylinder pressure indications.